The operating system. The Soviet Dragunov can shoot Heavy ball 178..185gr ammo, the same ammo would damage a PSL over time.
The Romanian PSL shoots only light ball 146...152gr ammo. It is an overgrown, accurized AK. They both use 7.62x54r ammo. That is the similarity. There is also the Yugo M76. Made in 7.62x54r and 8x57, and most recently 7.62x51.

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Freedom is not free. The best of us always leave too soon.

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"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

Seriously, the PSL was designed and manufactured in Romania to be a designated marksman rifle, not a sniper rifle. It's a beefed up AK-47 with a more powerful cartridge. It's intended for combat out to about 500 meters or so. It's about $800 on the open market. Here's mine:

The Dragunov, while similar in appearance, is Russian made, uses a different action and was designed from the ground up to be used at longer distances like a sniper rifle. I think they sell for a few thousand dollars. Here's a typical one:

Some companies that imported PSLs into the US called them "FPK Dragunovs," although they're really not Dragunovs. They just look similar.

The way I tell them apart:

1) There's a large gap (about an inch) between the front of the Dragunov's trigger guard and the rear of the magazine, while on the PSL there is no gap.

2) The PSL magazine has a big "X" embossed on the sides. The Dragunov mags look like waffles.

3) The Dragunov's safety lever has a dogleg bend in it, but the PSL's lever is straight like an AK's.

4) The Dragunov generally uses a Russian PSO-1 scope, while the PSL uses the Romanian LPS scope which doesn't have an electric reticle illuminator. (I.e. no wires.) Some people mount different scopes though, so it's not always obvious.